| 摘要 |
PROBLEM TO BE SOLVED: To provide a center defect prevention method for preventing a center defect attributed to an anvil used when a large-sized product is manufactured by cogging. SOLUTION: A center defect prevention method for a large-sized hard-to-work product is characterized in that when an upper anvil is reduced toward a lower anvil in a direction perpendicular to an axial direction of material to be forged comprising a large-sized hard-to-work steel ingot, and the material is subjected to cogging while being intermittently fed in the longitudinal direction, a reduction of area per one pass to the material to be forged is set to be in the range of 10-20% and also, W/H of the anvil used for the cogging is set to be 0.3-0.7 until the cross sectional area of the material to be forged becomes 100-50% of a blank material cross sectional area, and W/H of the anvil is set to be 0.8-1.2 until the cross sectional area becomes <50%-15% of the blank material cross sectional area. COPYRIGHT: (C)2009,JPO&INPIT
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